Here is a real world test of 4 years of comparisons I did in the field. Although not flawless it is darned extensive...
After 4 years of trials, 1 Set of Swarovski 8X42 EL, 2 Sets of Swarovski 10X42 EL and 1 pair of Leica HD-B, the jury is in.
I started with the 8X42 EL as I have preferred 8X for most of my optic use. I didn't care for the 8X as much as I have for the 8.5 in both the EL and later the EL Swarovision, so I tried the 10X EL range.
They were good glass and great range finders, although they aren't the quality of the Swarovision. They never were designed to be as good as the Swarovision and I knew that going in. I still wanted the benefit of the all-in-one package. I used them for around 2 years with good results.
The HD-B came out and had incorporated the Perger Porro-prism in the binoculars and everyone knows a porro-prism is better quality for the optic than a roof prism. I was anxious to use the Leica and see the advantage of the newest in optics and rangefinder.
Between the 2, the Leica was faster at ranging than the Swarovski and easily out distanced the Swarovski. I did have them to compare side by side and I eventually sold the Swarovski and used the Leica. All the ballistical information that can be downloaded into the Leica made no difference to me as I have ballistic reticles in my scopes and shoot accordingly. If all the programmable information is of value, this could skew your preference to to Leica over the Swarovski, I was only concerned about the rangefinding capabilities and optical quality.
I used the Leica for over 2 years, combined comparisons between the 2 are from 4 years of extensive field use. I also found the Leica to be on the upper end of usable size, any larger or heavier and they would be hard to realistically consider for that much use in the field.
There are many comparisons to be made;
Button for the rangefinder...Leica
Eyepiece...Swarovski
Focus wheels...Tie
Target size of lazer in eyepiece...Leica
Readability of rangefinder...Tie
Range distance...Leica
Size and feel...Swarovski, even with the 2 bellies in the tubes, you don't know they are there
Rainguards and objective covers...Swarovski
Optic quality...Swarovski, I was very disappointed with the optics of
the Leica, I expected more from them as their Ultra-vids, give up little to any optic made
There are more comments that can be added, but for the sake of a short/concise comparison, this is a good start.
I just sold the Leica HD-B and bought the last pair of Swarovski that Cabelas had. I am not interested in the newest Swarovski, as I am more interested in Swarovision quality in the optics of the binocular. Until either company comes out with an affordable set of ranging binoculars that has the optical quality of Swarovision, I will continue to use the Swarovski Ranging EL's.
The comparison of the 2 optics leans in favor of Leica, but I feel that the overall useability of the Swarovski is better and although they don't range as far, I will never be shooting anything past 1600 yards and the Swaro will easily do that. I do like the optical quality of the Swarovski and the way the eyepieces fit as well.
Swarovski wins at least for me...